Influence of processing method on the exfoliation process for organically modified clay systems. I. Polyurethanes

Abstract

The influence of different processing methods on the nature of the dispersion achieved in the creation of a polyurethane nanocomposite is presented. The nanocomposites were produced using two different types of organically modified montmorillonite clays and a sample of fine particles of silicon nitride as a reference material. Rheological data were used to assess the nature of the dispersion achieved using the different processing methods. The nature of the dispersion produced was characterized using wide-angle X-ray scattering measurements of the finally cured products. Dynamic mechanical thermal analysis was used to investigate the effect of the incorporation of clay platelets into the matrix of the polymer. The high-temperature modulus provides evidence of the interaction between the polymer and the clay platelets; however, surprisingly, the glass transition temperatures of the filled and unfilled materials were almost identical

Study of the factors influencing the exfoliation of an organically modified montmorillonite in methyl methacrylate/poly(methyl methacrylate) mixtures

“…There was little difference between the dispersion that contained the LMA and those that did not. In a previous paper, 9 it had been noted that the sonication power level appeared to have an effect on the degree of exfoliation. Using different sonication power levels, mixtures containing 5% (w/w) of Cloisite 30B were investigated (Fig.…”

“…8 In a previous paper, we reported the use of ultrasound to aid the exfoliation of organically modified montmorillonite (OMMT) in low molar mass poly(propylene glycol). 9 It was shown that in low viscosity media, high shear by itself may not be sufficient to achieve exfoliation. The additional use of ultrasound has been shown to provide an effective route to the dispersion of the OMMT platelets at a nano level.…”

Oxygen barrier property of polypropylene-polyether treated clay nanocomposite

“…Ultraturrax high-shear dispersion and PP-g-MA compatibilizer addition along with long alkyl chain for compatibility with PP were reasons for exfoliation of clay layers in the PP matrix. Ultraturrax high-shear dispersion lead to exfoliation of the clay layers, for researchers elsewhere [42,43].…”

Effect of different preparation routes on the structure and properties of rigid polyurethane‐layered silicate nanocomposites

“…The difference between various dispersion techniques such as high shear homogenizer and sonifier has also been compared. 7 Sonification can create better dispersion and more stable suspensions but there is evidence that ultrasonic energy can give rise to polymer degradation. 10 The in situ polymerization reaction pathways and kinetics have not been well investigated for PU nanocomposite systems.…”

“…However, processing is usually not the focal point of these studies [7][8][9] and normally not investigated systematically. Furthermore, the processing for elastomeric systems tends to be less complex than the more reactive rigid PU systems.…”